Chemical Senses

Question 1

What do receptor cells do?

Answer 1

Transduce an environmental signal into electrochemical signaling of the nervous system

Question 2

What are chemical senses?

Answer 2

Chemical properties of molecules trigger response from specialized receptor cells

Question 3

What is the importance of taste?

Answer 3

1.) Evolved as a way to detect foods/liquids that have nutrients
2.) Used to reject foods that are toxic

Question 4

What are the 5 general classes of taste?

Answer 4

1.) Sweet
2.) Sour
3.) Salty
4.) Bitter
5.) Umami

Question 5

What is umami?

Answer 5

A savory taste of glutamate and its derivative forms

Question 6

Where are the receptors of the taste organ found?

Answer 6

1.) Tongue
2.) Palate
3.) Pharynx
4.) Epiglottis

Question 7

Where are the taste buds found?

Answer 7

In papillae

Question 8

How many receptor cells are on a taste bud?

Answer 8

50-150 taste recpetor cells

Question 9

What is the perception of flavor?

Answer 9

A response to chemical properties of substances on the taste receptor cells

Question 10

What is a taste pore?

Answer 10

An opening at the top of the taste bud formed by microvili

Question 11

What are microvili?

Answer 11

Small thread-like projections from the TRCs

Question 12

How often do taste receptor cells regenerate?

Answer 12

About every 2 weeks

Question 13

What do TRCs stimulate?

Answer 13

Basal cells and afferent neurons

Question 14

Taste receptor cells are surrounded by ______ and connected to _____________

Answer 14

basal cells; afferent gustatory neurons

Question 15

What is the difference between an EPSP and a receptor potential?

Answer 15

EPSP happens in neurons; receptor potential happens in receptor cells with the stimulus coming from the external environment

Question 16

What molecule creates favorable gradients to taste salt?

Answer 16

Na+

Question 17

What molecule creates favorable gradients to taste sourness?

Answer 17

H+ and blocks K+

Question 18

What molecule creates favorable gradients to taste sweet, umami, and bitter?

Answer 18

G-Protein coupled receptors

Question 19

How many sweet receptors are there?

Answer 19

1

Question 20

How many umami receptors are there?

Answer 20

1

Question 21

How many bitter receptors are there?

Answer 21

Many

Question 22

NaCl is perceived as _____

Answer 22

Salty

Question 23

Quinine is perceived as _____

Answer 23

Bitter

Question 24

HCl is perceived as ______

Answer 24

Sour (Acidic)

Question 25

Sucrose is perceived as ______

Answer 25

Sweet

Question 26

What is the result of TRC depolarization?

Answer 26

Release of excitatory NT to synapse with gustatory afferent neurons

Question 27

Gustatory Afferent Neurons travel to the brain as what 3 cranial nerves?

Answer 27

1.) Facial Nerve 2.) Glossopharyngeal Nerve 3.) Vagus Nerve

Question 28

With taste, the Facial Nerve is responsible for...

Answer 28

Anterior 2/3 of tongue

Question 29

With taste, the Glossopharyngeal Nerve is responsible for....

Answer 29

Posterior 1/3 of tongue

Question 30

With taste, the Vagus nerve is responsible for....

Answer 30

Little bit of TRC from the epiglottis

Question 31

What is the pathway from the nerves to the brain for gustation?

Answer 31

1.) Gustatory Afferent Nerves 2.) Medulla 3.) Thalamus 4.) Cortex

Question 32

What is spontaneous activity?

Answer 32

Neural firing in the absence of a stimulus

Question 33

Where does smell come from?

Answer 33

Molecules evaporating off from matter

Question 34

What percent of distinct odors evoke negative reactions?

Answer 34

80%

Question 35

What is the purpose of smell?

Answer 35

To protect against ingestion/inhalation of toxins more than enticement to take in something good

Question 36

What are the 3 types of cells in the Olfactory Epithelium?

Answer 36

1.) Olfactory Receptor Cells 2.) Supporting Cells 3.) Basal Cells

Question 37

What is the purpose of Supporting Cells?

Answer 37

Assist ORCs and produce mucus

Question 38

What is the role of Basal Cells in the Olfactory Epithelium?

Answer 38

To become ORCs

Question 39

How often are olfactory receptor cells replaced?

Answer 39

Every 4-8 weeks

Question 40

What is mucus made of? (6)

Answer 40

1.) Water 2.) Sugars 3.) Proteins 4.) Salts 5.) Antibodies 6.) Odorant Binding Proteins

Question 41

What is the role of antibodies?

Answer 41

Needed because infectious agents can enter the body through the ORCs

Question 42

What is the role of odorant binding proteins?

Answer 42

Helps concentrate odorant molecules in the mucus

Question 43

What do odor molecules bind to in the ORCs?

Answer 43

Cilia

Question 44

Axons from ORCs extend through the __________ to enter the cranium

Answer 44

Cribiform Plate

Question 45

What are the 6 steps of ORC depolarization?

Answer 45

1.) Odor molecule binds to GPCR 2.) Triggers intra-cellular signaling 3.) Opens Na+ and Ca2+ channels, which opens Cl- channels 4.) Positive charge flows in 5.) Negative charge flows out 6.) Depolarization

Question 46

What is transient smelling?

Answer 46

Smell sensation fades quickly

Question 47

What are the 2 reasons for transient smelling?

Answer 47

1.) Enzymes in mucus break down the odor molecules 2.) Response from ORCs adapts

Question 48

What is adaptation?

Answer 48

Decreased response despite continued presence of the stimulus

Question 49

What is the central olfactory pathway?

Answer 49

Direct pathway from CN1 to olfactory complex

Question 50

What is Anosmia?

Answer 50

Reduction in smell sensitivity

Question 51

What is the most common cause of anosmia?

Answer 51

Nasal Congestion

Question 52

What are 5 other causes for anosmia?

Answer 52

1.) Nasal polyps 2.) Traumatic injury to cribiform plate and ORC axons 3.) Inhaled toxins 4.) Medications 5.) Aging

Question 53

How does anosmia cause/exacerbate dysphagia symptoms?

Answer 53

Loss of taste and smell impair oral prep phase